Ladder counterbalancing apparatus



June 17, 1947. H. J. TROCHE ET AL LADDER COUNTERBALANCING APPARATUS 2 Sheets-Sheet 1 Filed May 3, 1945 S 4 y 4 a F A .fl 4 I w/am Lu 0% WM U o 4 M 2 o I 2 w I 2 48 7 o 3 0 f o 0 7 o swam/tom E am am e A 1F. MJ u #m f attmf June 17 1947. 1 H. J. TROCHE ET AL 2,422,507

LADDER COUNTERBALANCING APPARATUS Filed May 5, 1945 2 Sheets-Sheet 2 u, l "c -m fir 35 38 //f/PMA(V 171M015.

T J ALWMIF'AREAR /;441, 7m

latentecl June 17, l47

"UNITED STATES PATENT orno-E A j.. 7., a, eD NT fie w Nqi f dBi Herman J. "Pro che (Lflleveland; and J -Farrar, 2 Cleveland,; ()hio,; assignorsi-to 'I he American Coach '8iBody Company, Cleveland, Ohio,acorporation of Ohio It: at;

Application'May 3,1945, Serial N'."'591,756

ingra ladder thereon that is swingable and tiltable 8Clairns. (01. 228 13) 1;;

ags; 3 an i are-views gim lam mg ;gene at ng with reference-to the vehicle for obtaining access to overhead traliic lights, streetlamps and thelike,

The invention comprises in general an improvement onthe ladderconstruction thatisshown in Unitedistates Letters Patent No.. 2,238,665, issued April 15, 1941, for Utility. vehicle on an application fil d by Herman. J. Tro'che,

Briefly, the ladder illustrated in patent is supported upon a sleeve which in turn is supported upon a column thattisattachedto the vehicle floor. Thelladder is counterbalanced by spring loaded plungers which are disposedat each side'of the support within casings and which are 'connected'to the. ladder by fle'xible'cables.

While'such spring suspension is adequate tocounterbalance the ladder, nevertheless .we have the aforesaid found that in" cert'ain elevated positions of the,

ladder the force exerted by .the counterbalancing mechanism is not applied with suflicient degree of uniformityin the entire'range of tilting movement of theiladder, asa result of which more force must be exerted by the operator to shift'the ladder whenever it is in one position than when it is disposed'in another position. n

An object of the present invention is to improve the counterbalancin'g mechanism" so asIto achieve a counterbalancing force thatkwill be" substang tia'lly juIlifOrl'ln in its fcounterbalancinglfeffect for substantiallyfthe entire "range of tilting mo'vement of the; ladder whereby the aforesaid diffi cultjy mayjbe'readily overcome. I

A morespecifi'c object of the present. invention 5 isrt o' provide a, counterbalancing mechanism which, as the ladder is tilted towarda verticalposition, will. decreaseitsjfforce substantiallycom mensurate withthe decrease of the force of grav ity which: zontal position; t 1

ends to returnthe ladder to a hori- Other. objectsifan'dfiadvantaees oi the wil1f; becorne v moreapparent from the lfollowing description, reference being had; to the accompanyihg i drawings, 'fwliich I illustrate ..a preferred embodiment of the invention. .Thenoveljzfeatures 1 of the inventionwill ,be summarized in the claims.

Referring now: to the drawings; Fig; 1 is a .fragmentary new ofvl'a vehicle havihga laddenem dying the present invention; mounted thereon V and illustrating the-{ladderin various positions; Fig}? 'is airagmentary side elevationof a-ladder and supporting structure and illustrates theilad der iira horizontal position ior transportation m-knla w were certa n p tS ei e-- rok n away to 'more clearly illustrate theinvention its different tilted positions oftheladder fragmentary plan view of theladder and'supporting structure, the ladder being in the-position show-n in-aEigP-BU a V In 'the drawings, I the .laddereis shown as being I mounted upon the floor of ;a-vehicle ,v indicated in general at 4-0, and is of; the extensible:-type, there being two sections and 2& ZIhe sections are mounted telescopically with respect to each, other in, the customary manner the section "being the lower-or base-section and the section I 2 being the-upper or ezgtensible sectionr erence theretoQUand tOr. tilting movement to any desired angle withiniit s range .l The} supporting structurefor the ladder mayrcomprisea column in the, form ot a vcylinder} l4! that; .projectsT up- Wardly; from. .abase 45, which. is "fastenedrto vthe fioorot-thet'vehicle oemed fthe"comm tor rotationabout-the axis thereofis asleeLve lfi' which extends downwardlyaroundjthe column 'l l'as indicated inLFigLIZrl.

and the. other end of which' is 'pivotallyaconnected to theadjacen't siderailof thebasej'section l ljof" the laddelx'ias atQZV iQ .A jlink '25lis. also pivbtally connected to; the; ladder .atj2'4 and to a, second linkf'l 26, as at 2 1., 1T heolink 216m .lllllllis pivdted tojthe sleeve .1 6 ataepoint 28 -.vvhich' s spaced frio'm' ithe pivot 21 The position" lofthe, struts 20 is deter? mined, by threaded shafts 30 "which": are carried by aro sin 3 l7. pivotally connectedfto the s eeve it?" The shafts 30 are simultaneously actuated by either wheel of a pair of hand wheels' 32 se cured to, ancross rshaft 33;, v"The shaft geared to the shaftsfiallwhi'ch coactiwithifspectivenuts ,pivotallyjmountedi'in, enclosures a l {w ic are "S'e cunecltil .the struts" Theiljadder. is: in a .horizfiontaljpofsition, as

operatondrawslfth.end'.flliof he ll wardly'rand l. latchSLit to 1th The;- ladderis supported on the vehicle Ifor swinging movement. :in .-.an entire circle" withr ref- The ladderiis connected; sleeve Joya sys".

3 state that the latch may be manually actuated, as for instance by a control member I8 (Fig. After the ladder has been latched in its tilted position, indicated at B in Fig. 1, it may be adjusted by manipulation of the hand wheel 32 to the desired angle of tilt, as for instance, the posi- I tions C of Fig. 1. e

The present invention is particularly concerned with an improved mechanism for counterbalancing the ladder to facilitate its movement to the tilted position and to maintain the strain on the tilting apparatus. This mechanism comprises a spring loaded plunger carried by and extending alongside the ladder and controlled by a system of parallel links which are connected to the sleeve l6.

As shown in the drawings, a link 35 is pivoted at one end, as at 36, to the bracket 23 and at its other end, as at 31, to a bracket 38, which in turn is pivoted to the ladder at the pivot 24 heretofore described. The arrangement is such that the pivots 36 and 2| are spaced horizontally fromspring loaded plunger 49 which is pivoted at 4| to an upstanding arm 42 of the bracket 38. This,

plunger extends alongside the ladder into a cylinder 43, the far end of which is pivoted at All to the ladder section II. A pre-loaded spring 45 is interposed between an enlarged end 45 of the plunger and the end 4'! of the cylinder.

By utilizing parallel links and to connect the bracket 3,8 to the collar 23, the part 38 is maintained in a vertical position during all increments of movement of the ladder about the pivot 24. As a result, the lifting force of the springs can be applied to the ladder in a degree more nearly approximating the shifting of the center of gravity of the ladder structure .so as to cause a substantially balanced condition regardless of the position of the ladder with respect to the supporting structure. Normally, where the ladder is horizontal, the moment arm about the pivot 24 does not change as rapidly when the ladder is near a horizontal position as it does when the ladder approaches the vertical position. By maintaining the part 38 substantially vertical, however, during the swinging movement of the ladder, the springs are able to exert a counterbalancing force of substantially uniform degree regardless of the position of the ladder with respect to the supporting frame. As a result the operator can move the ladder, by applying subtantially the same force thereto, in all positions of the ladder.

We claim:

ladder, and with a lever, a pivotal connection between the other link and the lever and a pivotal connection between the preloaded plunger and said lever.

2. In combination, a vehicle, a ladder, means for mounting the ladder for swinging and tilting movement on the vehicle, said means comprising a column rigidly attached to the vehicle, a sleeve swivelled on the column, a pivotal connection between the sleeve and the ladder, and counterbalancing means connecting the sleeve and ladder, said last-named means including a preloaded plunger having one end pivotally connected to the ladder and extending alongside a rail of the ladder, a lever pivotally interconnecting the other end of said plunger with the ladder, and means to control the position 0f said lever including a pair of parallel links interconnected between the lever and the sleeve, each of said links being pivoted at one end to spaced points on said lever and at the other end to spaced points on said sleeve.

3. In combination, a vehicle, a ladder, means for mounting the ladder for tilting movement on the vehicle, said means comprising a column rigidly attached to the vehicle, a sleeve supported.

by the column, and counterbalancing means connecting the sleeve and ladder, said last-mentioned means including a preloaded plunger unit pivotally connected to the ladder, and a link pivotally interconnected between the other end of the plunger unit and said ladder, and a system of parallel links connecting said link to said sleeve. 4. In combination, a vehicle, a ladder, means l for mounting the ladder for tilting movement on 35' the vehicle, said means comprising a column rigidly attached to the vehicle, a member rotatably supported on the column, and counterbalancing means connecting the member and ladder, said last-mentioned means including a'pair of parallel links, each link being pivoted at one end to the member at spaced points, one of said links having its other end pivoted to the ladder, a third link pivotally interconnecting said first-named 5. In combination, a vehicle, a ladder, means for mounting the ladder for swinging and tilting movement on the vehicle, said means comprisin a column rigidly attached to the vehicle,

a sleeve mounted on said column for swingin-g movement about 'a substantially vertically extending axis, a pivotal connection between the sleeve and ladder including a link pivoted at one end to said sleeve and at the other end to said ladder whereby said ladder may be, tilted about 1. In conlbinatiomavehicle, a ladder, means V for mounting the ladder for tiltingmovemeht on said last-named means including a system of parallel links one end of each link being;piv-

otally connected to the sleeve; the other end of one link being pivotally connected with thea horizontal axis, a. second link pivoted atjone end to said sleeve, and connecting means pivoted to the pivotal connection between the ,firstnamed link and the ladder, and pivoted'to the second-named link to maintain said links" parallel, and. a preloaded compression spring disposed between said; connecting means and apoint on said ladder remote from its pivotal conneaj tending axis, a: pivotal connection between the sleeve and ladder including a link pivoted at one end to said sleeve and at the other end to said ladder, whereby said ladder maybe tilted about a ladder, means 7 a horizontal axis, a second link pivoted at one end to said sleeve and connecting means pivoted at the pivotal connection between the first-named link and the ladder and to the second-named link to maintain said links parallel, a plunger member, a cylinder member cooperating therewith, a compression spring coactin with the plunger and cylinder and tending to move them together, a pivotal connection between one of said members and said connecting member, and a pivotal connection between the other of said members and said ladder at a point remote from its pivotal connection with said first-named link.

7. In combination, a vehicle, a ladder, means for mounting the ladder for swinging and tilting movement on the vehicle, said means comprising a column rigidly attached to the vehicle, and a sleeve swiveled on the column, and a strut pivotally connected to the sleeve and to the ladder, and an additional connection between the sleeve and ladder comprising a pair of links pivotally joined together, said means also including a screw and nut couple connecting said strut and the sleeve for moving the ladder with reference to the sleeve, means for actuating one member of the couple, a link pivoted at one end to said sleeve, means interconnecting the pivotal connection between the strut and said ladder with the last-named link to maintain said link parallel with said strut at all times, and a preloaded compression spring positioned between said connecting means and a point on said ladder remote from its pivotal connection with said first-named link to counterbalance said ladder.

8, In combination, a support, a ladder mounted on said support for swinging movement in a substantially vertical plane, a counterbalance for said ladder including a telescoping preloaded spring cylinder, a lever, a pivotal connection between one end of said cylinder and the ladder, a pivotal connection between the other end of said cylinder and the lever, a pivotal connection between the other end of said lever and the ladder, means to control the swing of said lever about its pivotal connection with said ladder and thereby control the counterbalancing force of said spring cylinder, and wherein said last named means includes a pair of parallel links, said links ldeing pivotally connected at one end to respective spaced points on said lever, one of said last named connections being coincident with the pivotal connection between the lever and the ladder, and pivotal spaced connections between the other ends of said links and said support.

HERMAN J. TROCHE. ALVIN J. FARRAR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

